Different Precipitant Preparation of Nickel-Doped Mn/TiO2 Catalysts for Low-Temperature SCR of NO with NH3

Abstract

The Mn-Ni/TiO2 catalyst was prepared by co-precipitation method and investigated for the low-temperature selective catalytic reduction (SCR) of NO with NH3 in this work, and Mn-Ni/TiO2 catalysts were prepared by different precipitants respectively such as sodium hydroxide, carbamide, ammonia or hydrogen peroxide. The microstructure and performance of catalysts were investigated. The activitiesof catalysts prepared by different precipitants were studied in the temperature range 90°C-350°C. The results show that Mn-Ni/TiO2catalyst prepared by CO(NH2)2-NH3·H2O-H2O2 compound precipitant has an extraordinary performance even at the low temperature of 120°C. H2-TPR results show the peak positions shift to lower temperatures, standing for the reduction potential of MnOx species is increased compared to those of Mn/TiO2 catalysts. The interaction of Ni and Mn atoms is beneficial to an enhancement of the oxygen mobility due to CO(NH2)2-NH3·H2O-H2O2 as precipitant. It is worth noting that the low temperature peak area increased by adding hydrogen peroxide as precipitant. NH3-TPD results illustrat that for the Mn/TiO2 and Mn-Ni/TiO2 catalysts which are attributed to NH3 desorbed by weak acid sites and Brønsted acid sites.